1. Field of the Invention
The present invention relates to a developing unit used in an image forming device such as a copy machine, a printer and a facsimile machine for adhering a developer on an electrostatic latent image and developing the electrostatic latent image, and to an image forming device having the developing unit.
2. Description of the Related Art
In an image forming device, when carrying out an image forming process by adhering a developer (toner) on an electrostatic latent image carrier on which an electrostatic latent image is formed, a remaining amount of the developer decreases with the use of the developer in the image forming process. Therefore, it is necessary to replenish the developer as needed. Thus, the developing unit is formed capable of being inserted and removed with respect to the image forming device. When necessary, the developing unit is removed from the image forming device and the developer is replenished or the developing unit is replaced. However, if the developing unit is not positioned properly with respect to the electrostatic latent image carrier, the developer is not adhered evenly on the electrostatic latent image carrier and unevenness is generated in the image forming process.
In consideration to such drawbacks, for example, according to a first conventional image forming device, two pressure rollers are provided at both ends of a developing sleeve, respectively. A transferring direction of the pressure rollers is regulated by a pair of regulatory members having a surface parallel to a straight line that connects centers of a photoconductive drum and the developing sleeve. The pressure rollers are pressured toward the photoconductive drum by an elastic member such as a spring. According to a second conventional image forming device, gap rollers are provided at both ends of a developing roller to provide a surface of a photoconductive drum and an axial center of the developing roller at a prescribed interval.
According to the first conventional image forming device, the transferring direction of the pressure rollers is regulated by the pair of regulatory members and the developing sleeve is positioned. However, since a pressure force for the photoconductive drum is applied to the pressure rollers, if a positional relationship between the regulatory members and the pressure rollers is not set precisely, a positional relationship between the photoconductive drum and the developing sleeve is displaced and the developer cannot be moved evenly from the developing sleeve to the photoconductive drum. According to the second conventional image forming device, a structure for accurately positioning the gap rollers with respect to the surface of the photoconductive drum becomes necessary.